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    Written by: LEUNG Wai-hung     September 2010

  1. In July and August 2010, severe forest fires occurred in the western part of Russia.  Smoke from many fire sources over an extensive area can be seen from the satellite picture (Figure 1).

    In 1986, parts of the western Russia, Belarus and Ukraine were contaminated by the fallout from the Chernobyl accident.  If the forest woods were burnt by the fires, radioactive materials might be released into the atmosphere. According to the analysis of the Institute of Radiological Protection and Nuclear Safety in France, however, the polluted substances transferred from soil to woods have a rather low level of radioactivity.  It is expected that the radioactivity arising from burning of the forest woods would be similar to that of natural radon gas in the air.  Therefore, the fires would not pose any radioactive hazard to the residents nearby.  Nevertheless, it should be noted that the toxic smoke and particulates produced by the fires were harmful to health.

    Besides, people were concerned about whether the nuclear facilities in Russia would be affected by the forest fires. The fires had once raged near Savor, a town in western Russia with major nuclear research facilities (Figure 2). According to media reports, Russian officials said that Sarov was not affected by the fires and all explosives and radioactive substances had been temporarily removed from the town.  An 8-kilometre trench was also dug by the Russian army to prevent the fires spreading to Sarov.

    Readers may be interested to know whether the particulates released by the Russian forest fires pose any threats to Hong Kong.  The location of the fires was more than 6000 kilometres northwest of Hong Kong.  Figure 3 shows the trajectories of air reaching Hong Kong from June to August 2010. As there was no air mass coming from the northwest during the period, Hong Kong was not affected by the particulates.

    Figure 1  Satellite picture showing smoke from a number of fire sources over the western part of Russia.  The red spots in the picture depicted suspected locations of the fire. (Source of image: NASA/GSFC, MODIS Rapid Response System,, image time: 11 August 2010, 09:25UTC/17:25HKT)
    Figure 2  Map showing location of Sarov and the western part of Russia. (Source of image: Google Maps)

    Figure 3  Backward trajectory of air mass reaching Hong Kong from June to August 2010

  1. References:

  2. "MODIS Rapid Response System", Goddard Space Flight Center, NASA.
  3. Institut De Radioprotection Et De Sureté Nucléaire (Institute of Radiological Protection and Nuclear Safety), France.
  4. CNN World News.
  5. BBC News.

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Last revision date: <22 Jan 2013>